Super quick post.
I use a Samsung Galaxy Note 3 smartphone as a GPS as it has a nice big screen. To keep it dry I bought an Ortlieb A5 waterproof document bag to keep it in.
Recently the phone became difficult to remove from the bag. The screen stuck to the plastic and, after a few struggles, I gave up keeping it in the case. Afterwards I noticed that the screen was unusually dirty but thought nothing of it, just developed the habit of frequently cleaning the phone with a soft cloth. However, after a few weeks, I took a closer look and noticed something weird.
There are permanent marks on the screen which are only visible when the screen’s dirty. They look like regular greasy patches but after a clean they reappear, identically, as soon as I touch the screen. In sunlight they make the screen very difficult to see.
A google search revealed that smartphone screens (including Samsung’s) have an oleophobic coating that’s lipophobic and hydrophobic. i.e. It repels fingerprints. These coatings can become damaged and it sounds like this is what’s happened to my phone. This kind of damage isn’t covered under warrantee but I’ve managed to save my phone. Cleaning the screen removed the marks and adding a screen protector covered up the damaged areas so they can’t get greasy and reappear. Phew!
Although I can’t be 100% sure that the document case caused the damage it’s the most likely explanation. Ortlieb don’t advertise this case as a phone cover or protector so the product can’t be blamed for what happened. I just want to let people know, probably best not to use these document cases as waterproof phone cases, just in case.